Vacuum may be generated during throttled engine operation but the operation of turbochargers may, however, reduce the amount of vacuum delivered to the intake manifold of the engine. Thus systems that may generate vacuum for other vehicle applications that rely on low pressure actuation without compromising the efficiency of the engine are desirable. DE 102014222714 A1 discloses the possibility of vehicle systems comprising various vacuum consumer devices which are actuated by means of a vacuum. This includes a brake booster, for example. The vacuum used by these devices may be provided by a special vacuum pump. In further embodiments one or more aspiration devices may be incorporated into the engine system which are capable of utilizing the air flow in the engine and using it to generate a vacuum.
The inventors herein have recognized potential issues with such systems. In one example, vacuum pumps may be parasitic and result in energy waste. As another example, vacuum pumps may increase the packaging space of the engine and increase the cost and complexity of the vehicle.
Accordingly, the inventors herein propose an approach to at least partly address the above issues. In one example, a pressure tapping device may include a fluid-carrying connection to a fuel line and may be configured to transmit a proportion of pressure energy of the fuel to a working medium, physically separate from the fuel. The pressure tapping device, according to the disclosure, may be used in a motor vehicle which comprises an internal combustion engine and a fuel storage reservoir connected to the internal combustion engine by a fuel line, wherein the fuel may be stored in the fuel storage reservoir at a storage pressure greater than an ambient pressure and thereby possesses pressure energy. According to the disclosure the pressure tapping device has a fluid-carrying connection to the fuel line and is configured to transmit a proportion of the pressure energy of the fuel to a working medium, physically separate from the fuel. The pressure tapping device advantageously allows use to be made of the pressure energy inherent in fuel that is stored under pressure, such as compressed natural gas (CNG), for example.
In one example of the pressure tapping device according to the disclosure, the device may comprise an admission line with an admission line pressure control valve and a discharge line with a discharge line valve. This makes it possible to feed fuel through the pressure tapping device and to limit the minimum and maximum working pressure. In another example of the pressure tapping device, the device comprises a pressure transmitter, including a first cylinder with a first piston and a second cylinder with a second piston having a fluid-carrying connection to the first cylinder. A transmission fluid is located between the first piston and the second piston. The admission line and the discharge line have a fluid-carrying connection to the first cylinder.
The pressure tapping device according to the disclosure may be integrated into a motor vehicle. The motor vehicle comprises an internal combustion engine and a fuel storage reservoir connected to the internal combustion engine by a fuel line. The fuel may be stored in the fuel storage reservoir at a storage pressure greater than an ambient pressure and thereby possesses pressure energy. Here the pressure tapping device has a fluid-carrying connection to the fuel line. The motor vehicle may be operated more efficiently with the pressure tapping device since conventional devices, such as pressure pumps and their drive, can be eliminated.
In another example of the motor vehicle, according to the present disclosure, the pressure tapping device is connected to a pressure-operated actuator of the motor vehicle. The actuator can therefore be operated by the pressure energy obtained from the fuel. The pressure-operated actuator may be, in this example, a brake booster. A greater pressure differential can be generated in the brake booster by the pressure tapping device than by a vacuum pump. This allows a greater boost for the same brake booster design size.
In another example, a method for operating a vehicle with a pressure tapping device includes supplying fuel to an engine from a fuel storage reservoir via a fuel line and transferring pressure energy from the fuel storage reservoir to a brake booster by the pressure tapping device. In one example, the method may further include opening an admission line pressure valve. By opening the admission line pressure valve in the admission line, fuel is diverted to the pressure tapping device, thereby transmitting a portion of the pressure energy to the brake booster via a working fluid housed within the pressure tapping device. The working fluid is then depressurized by opening the discharge line valve disposed in the discharge line which then flows fuel from the pressure tapping device to the fuel line. Use is thereby made of pressure energy derived from the fuel pressure.
In an example of the pressure tapping method according to this disclosure, an actuator of the motor vehicle is operated by the pressure energy of the working medium. In particular, a brake booster is operated. In this way, the actuator is operated by the pressure energy obtained from the fuel. In brake-boosting, greater brake power assistance can be achieved than in conventional vacuum methods.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.